ensign staff

a staff at the stern of a vessel at which the ensign is flown.

Also called poop staff.

Origin of ensign staff

First recorded in 1700–10

When she struck, a number of men climbed up the ensign-staff, under an apprehension of her immediately going to pieces.

Thrilling Narratives of Mutiny, Murder and Piracy |Anonymous
For a moment the ensign-staff shook in his hands, as if whipped by a gale.

Fort Amity |Arthur Thomas Quiller-Couch
When she struck, a number of the men climbed up the ensign-staff, under an apprehension of her immediately going to pieces.

Reprinted Pieces |Charles Dickens
A large flag or banner, hoisted on a long pole erected over the stern, and called the ensign-staff.

The Sailor's Word-Book |William Henry Smyth

But strength beginning to fail, he was satisfied of the necessity of some respite, when he fell in with part of the ensign-staff.

Thrilling Narratives of Mutiny, Murder and Piracy |Anonymous